MATERIALS AND METHODS

Bronchi were examined from five men who suffered from asthma for periods of 10 to 46 yr before death (table I). The criterion we used for the diagnosis of asthma was a history of clinical evidence of reversible obstructive lung disease, a condition in which there was widespread narrowing of the bronchial airways that changed its severity over short periods of time, either spontaneously or under treatment, and was not due to cardiovascular disease (Ciba Guest Symposium, 1959). The main clinical characteristics were abnormal paroxysmal or persistent breathlessness, and wheezing, and in most cases relief by bronchodilator drugs (including corticosteroids). The distinction of asthma from chronic bronchitis will be discussed below. Patients 7, 8 and 9 had chronic bronchitis as well as asthma, but asthma was the principal disorder in the opinion of the experienced chest physicians who took care of them.

Details of the controls and chronic bronchitics were given in a previous article (Hossain and Heard). In all cases, including asthmatics, the questionnaire described in the previous article was sent to the family doctor to obtain data on the previous respiratory symptoms. An intact left lung was removed at necropsy and fixed in distension by pressure-fixation (Heard, 1958, 1969): 4 per cent. formaldehyde in saline was perfused into the main bronchus and pulmonary artery at a pressure of 25-30 cm of fixative for a minimum period of 72 hr, with the pulmonary veins ligated.